Dental implants are used to secure a prosthetic received and other dental items in the oral cavity. One of the important goals of implant therapy is to achieve a firm, durable, intra-oral connection to the maxilla and mandable with a screw-type or cylinder-type structure made of a biologically compatible material. However, implant placement is often compromised by the quality of bone and available ridge width.
The creation of an osseotomy site for placement of implants by means of drilling is well known in dentistry. However, valuable bone tissue is removed during drilling, consequently fitting strength of an implant is not guaranteed, particularly when the surrounding bone issue is soft and porous. The bone tissue can be categorized into various bone classes. It is well known in dentistry that the bone of the upper jaw, or the maxilla, is considerably softer than the bone of the lower jaw, or the mandable. The bone of the upper jaw can be compared with balsa wood in terms of its strength. Osteoporosis, the structural change of the bone tissue due to age, also results in porous and soft bones. The drilling for the formation of osseotomy sites in the upper jaw for implant placement proves to be unfavorable, since bone tissue is removed from the soft bone. In the case of a narrow ridge, available bone tissue and bone density are critical to the quality of the resulting implant placement.
The alternative non-drilling devices and methods presently used for preparing osseotomy site for placement of dental implant are based, to a large degree, on an instrument named osteotomes. Osteotomes, developed by Dr. Summers in late 1980, comprises a handle-like holder and a shaft with a working tip having a circular cross section, and it has the shape of a graduated round rod. Osteotomes are available in several sizes with increasing diameters. They are frequently used by dentists to perform a required bone expansion for placing a dental implant.
In use, the working tip of the osteotome is placed on the bone base and the osteotome is introduced by tapping the top of the osteotome with a mallet or small hammer. As the introduction of the osteotome progresses, the next largest instrument is inserted into the osseotomy site formed. The implant bed is created by means of expanding and compressing the bone tissue. The working end of osteotome can be concave or round. The penetration depth of the osteotome is determined by means of markings. By pressing in the dental instrument to form the osseotomy site, the bone tissue of the jaw is displaced and compacted for receiving the dental implant. After implant placement, new bone tissue is formed around the implant. Therefore, no bone tissue is removed using osteotome technique, instead the bone tissue, especially the soft bone is compacted.
Comparing to drilling procedure, osteotome technique has many advantages. The compacted surrounding bone tissue prepared by osteotome method has higher bone density. The use of osteotomes allows implant placement in areas of limited bone width; improves initial implant stability and implant success in maxilla. It has been reported that the osteotome technique increases new bone formation and leads to an enhanced osseointegration of dental implants in jaw bones.
However, the osteotome technique is also a traumatic technique, consequently, it is accompanied by various disadvantages. Among the most important disadvantages, one is the damage to the bone, up to and including breaking and chipping of the bone, as a result of tension created at the dental base with each tap of the small hammer onto the osteotome. In some instances, a complete deterioration of the dental base can occur, and this deterioration of the dental base requires extensive repairs. Another disadvantage is the formation of simple, slightly conical cavities in the jaw, which does not provide a reliable bed for the fixation especially of screw-type implants. Since implants have different outer contours, particularly graduated cylinder implants with screw threads, the smooth, slightly conical osseotomy site formed in the jaw by osteotome is not structurally complementary to the threaded implants. This can results in difficulty in the osteointegration and difficulty in the cohesion based on an incomplete contact between the implant and bone. A further disadvantage is the alignment defect of the fixation axis because the bone expansion can not be controlled or adjusted. An additional disadvantage is the appearance of a hammer, the shock of the hammer on the metal and resulting fear of the patients.
U.S. Pat. No. 6,146,138 (to Dalmau) discloses a non-traumatic expansion device and a method of use. The expansion device has a threaded end having a shape of an elongated cone. The thickness of the threaded head is dependent on an expansion to be required. This device has the function of a screw for the purpose of drilling bone and keeping the bone mass. However, the screw threads do not correlate to the implant structure, and the prepared bed does not ensure proper implant contact into surrounding bone issues. If the implant thread does not match the expander, the bone will be pulverized by the implant threading into the site.
Because of the above described disadvantages, there exists a strong need for the development of new devices and methods which can reduce the problems associated with the existing techniques, and improve the techniques of bone expansion to achieve a better quality of dental implant therapy.